/Engine/Source/Runtime/Slate/Public/Framework/MultiBox/MultiBoxBuilder.h
Adds a tool bar stack button
void AddToolbarStackButton ( const [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< const [FUICommandInfo](API\Runtime\Slate\Framework\Commands\FUICommandInfo) > InCommand, [FName](API\Runtime\Core\UObject\FName) InTutorialHighlightName )